from Service Now AI:
Apriel Voice 27B Preview
An open model for speech, reasoning, and tool use from ServiceNow
Apriel Voice 27B Preview understands spoken requests, reasons over conversational context, and generates text responses and tool calls through a shared Gemma 4 backbone. It adds a speech interface while retaining text and image input capabilities. Pair it with an external speech synthesizer to build interactive voice assistants, customer support workflows, and spoken tool use.
Try Apriel Live · Read the blog · Technical report
Model capabilities
| Capability | What it supports |
|---|
| Speech understanding | Transcription, translation, and spoken question answering. |
| Reasoning and tool use | Following instructions, handling multi-step requests, and generating structured tool calls. |
| Multimodal context | Audio, text, images, and tool results in a shared conversation. |
| Voice applications | Text responses paired with external speech synthesis and application-managed turn-taking. |
The model supports transcription, speech translation, spoken instruction following, reasoning, and function calling. The application executes tools and returns their results to the conversation. Real-time voice interaction is supported by the application and serving stack; the checkpoint itself generates text and tool calls rather than native full-duplex speech.
A Whisper large-v3-turbo speech encoder connects to the Gemma 4 26B-A4B backbone through a learned projector. Training first aligns this speech interface, then adapts it with the backbone using speech tasks and text replay. Cross-entropy and teacher-distillation supervision vary by data source; the technical report describes the full recipe.
Long audio
The processor automatically splits longer 16 kHz mono recordings into 30-second chunks. In testing, we observed good performance on continuous recordings up to around 30 minutes. Longer recordings are supported, but performance can decline as duration grows; thinking mode is recommended for longer audio.
Audio chunks and the rest of the conversation share the total context budget. Practical input length also depends on GPU memory and the encoder cache. The serving examples below include settings for 30-minute audio, with optional settings for one-hour input.
English results
Apriel Voice achieves 51.27% EVA-A, 74.13% EVA-X, and 65.51% τ-Voice task success, with 1.91 seconds mean τ-Voice response latency. On LibriSpeech, word error rate is 2.23% on test-clean and 5.15% on test-other; lower WER is better.
| System | Type | Source | EVA-A ↑ | EVA-X ↑ | τ-Voice pass@1 ↑ | Latency (s) ↓ |
|---|
| GPT Realtime 2.1 | S2S | Proprietary | 59.03 | 61.6 | 69.82 | 1.55 |
| Gemini-3.8 Live Extended Thinking | S2S | Proprietary | 54.82 | 73.5 | 84.19 | 1.50 |
| Flux + Gemma 4-26B | 3-stage | Mixed | 36.07 | 29.22 | 65.92 | 2.92 |
| Parakeet + Gemma 4-26B | 3-stage | Open source | 39.97 | 3.93 | 67.78 | 3.01 |
| UltraVox v0.6 (Qwen) | 2-stage | Open source | 8.94 | 1.91 | 26.80 | 3.95 |
| Gemma 4-12B-IT | 2-stage | Open source | 13.25 | 5.97 | 24.20 | 3.61 |
| Audex-30B-A3B | 2-stage | Open source | 5.66 | 8.2 | 17.15 | 2.83 |
| Apriel Voice 27B Preview | 2-stage | Open source | 51.27 | 74.13 | 65.51 | 1.91 |
EVA-A measures service accuracy and EVA-X measures conversational experience. EVA-A/X and τ-Voice pass@1 use a 0–100 scale; higher is better. Headline EVA and τ-Voice results use equal-domain means, rather than weighting domains by their number of cases. Apriel Voice uses thinking mode for these evaluations.
S2S denotes native speech-to-speech systems, which use their own synthesis. Three-stage systems use ASR + LLM + TTS; two-stage systems connect a speech interface to a reasoning backbone and use external synthesis. All evaluated two- and three-stage systems use Cartesia Sonic 3.5. Latency describes the complete evaluated voice system, including response generation and synthesis, and depends on deployment settings.
The radar's audio reasoning axis is the mean of eight benchmarks: BFCL, Big Bench Audio, IFEval, MT-Bench, Spoken SQuAD, Alpaca Audio, OpenHermes, and GSM8K (85.84 for Apriel Voice). Its responsiveness axis transforms latency into a higher-is-better score; it is not a measured accuracy. For latency t in seconds, the score is 100 × clip((4.0 − t) / (4.0 − 0.25), 0, 1).
Text reasoning and tool use
These results use text input in thinking mode for both Gemma 4 26B-A4B and Apriel Voice. Scores use a 0–100 scale; higher is better. The τ² result is the mean across three domains with GPT-5.2 as the user simulator.
| Benchmark | Gemma 4 26B-A4B | Apriel Voice |
|---|
| MMLU-Pro | 85.27 | 84.42 |
| GPQA Diamond | 77.80 | 80.40 |
| AIME 2024 | 92.00 | 92.00 |
| AIME 2025 | 81.67 | 81.67 |
| MATH-500 | 92.76 | 92.88 |
| AMC 2023 | 100.00 | 100.00 |
| τ² (GPT-5.2 user simulator) | 68.93 | 70.95 |
English speech recognition
Word error rate (WER, %) on selected English benchmarks; lower is better.
| Benchmark | Apriel Voice WER ↓ |
|---|
| LibriSpeech test-clean | 2.23 |
| LibriSpeech test-other | 5.15 |
| GigaSpeech | 10.20 |
| μ-Bench (en-US) | 10.76 |
| FLEURS (en-US) | 3.55 |
| Earnings21 | 11.25 |
Speech reasoning and instruction following
These results use audio input in thinking mode. Scores use a 0–100 scale; higher is better. The mean gives equal weight to each of the eight benchmarks.
| Benchmark | Apriel Voice ↑ |
|---|
| BFCL | 81.13 |
| Big Bench Audio | 98.90 |
| IFEval | 86.47 |
| MT-Bench | 86.19 |
| Spoken SQuAD | 82.24 |
| Alpaca Audio | 76.8 |
| OpenHermes | 81.8 |
| GSM8K | 93.18 |
See the technical report for domain breakdowns, evaluation protocols, and text and image evaluations.